Check the error message given by the system in the failed process file. If it states:
DATA_SAVE_ERROR: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Data.SqlClient.SqlException: Violation of PRIMARY KEY constraint 'PK_xxxxxxxxxx'. Cannot insert duplicate key in object 'dbo.xxxxxxxxxx'.
The likely cause is there is the data file contains more than one unique field in multiple rows. For example: Course Codes must be unique. Removing the duplicated rows from the import file will allow the system to process the file correctly.